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Old Mar 29, 2008, 9:11 AM   #11
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Thanks JimC

also :



"Also someone told me that the 450d will have spot metering ... which the 400d doesnt ... is that of any importance to me ........ the price difference is abou $150 in both cameras ... should i be spending that much for spot difference?


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Old Mar 29, 2008, 9:19 AM   #12
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I wouldn't. It's my least used metering choice (I'd very rarely use it for anything). If I were doing a lot of studio work or still subject photography, it might come in handy taking spot readings from a variety of areas. But, you could just bracket your exposure and examine the images to determine best setttings, too.

For general purpose photography, unless you've got the time to take multiple readings on brighter and darker areas and use manual exposure or exposure compensation to get what you want, it's just going to cause problems trying to use it in most conditions unless you're very careful what you're metering on.

If you meter on an area that's too dark, you'll get an overexposed image, and if you meter on an area that's too bright, you'll get an underexposed image. You have to make sure you're metering on something relatively neutral (like a photographic gray card) using spot metering in most modes.

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Old Mar 29, 2008, 10:41 PM   #13
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As far as spot metering goes - I use it quite often when I'm taking pictures of flowers and sunsets. However,ALL of the street photography pictures I've taken that have wrong exposures were all taken when I forgot to change back to either center weighted or matrix metering. You might find it a liability for your purposes. While I find it useful and a "must-have" I could easily see where it wouldn't be worth much to you.
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Old Mar 31, 2008, 5:12 AM   #14
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Spot metering for stills and sunsets eh ...

The 400D has partial metering .... The website explained it but with words like exposure andaperature etc it sounded like french to me ...

In simple lay man terms what do partial and spot metering do ??.... i.e how will it imporve my pic ... will i be lost without it ?? Im asking cause most websites state this as a must have in art photography but i cant understand the techs that they are basing it on ...... So, if i am to take like say the picture ofa sunsetor of leaves and dew drops or of any still object i want to express as an art form ... will i really need spot metering??

Also if spot metering option is not availableonone perticularcamera ... (im assuming that spot meteringoptions can be turned on automatically by pressing a button on cameras it is availble on) .... can i still get the same effect by changing things manually .... although i really dont know what it is i could change ....

Also id like to apologise if im asking stupid questions ....( im just really interested in this and for the life of me cant undersatnd why i never picked a camera before) ....

.....Just bear with me and THANK U !!
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Old Mar 31, 2008, 8:03 AM   #15
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All the metering system is doing is measuring the light.

The different metering modes are just influencing how that light is measured.

The light measurement is then used so that the camera knows what Shutter Speed and Aperture is needed to expose the image for a given ISO speed (or so that you can better decide what shutter speed and aperture to use if you're using manual exposure, letting the meter act as a guide to whether your images are going to be too bright or too dark).

The EOS-400D/XTi has a Partial Metering system that's a small area around 9% of the frame. That's the closest to most other manufacturer's spot metering.

It's also got a Center Weighted Metering mode that places more emphasis on the center of the frame, while still taking the rest of the frame into consideration. This is usually the most predicatible metering system with most cameras.

It's also got a Matrix (a.k.a., Multi-Segment) metering system. This type of system looks at the entire frame, and tries to decide how to expose the image. This type of system is usually the least predictable in harsher lighting, with the algorithms used varying a lot between manufacturers. For example, some systems lean more towards protecting the highlights (brighter areas) than others, which can result in underexposed images in harsher lighting. In most cases, the focus point is weighted more heavily using Matrix Metering. But, how much the focus point is weighted also varies a lot. For example, my Maxxum 5D weights it very heavily in some lighting (which also means you have to be careful of your focus point using it, if your subject is not relatively neutral in brightness).

Metering behavior can vary significantly between manufacturers. So, you'll need to become more familiar with how the camera you choose handles metering for different types of scenes for best results.

That way, you can adjust the exposure for unusual conditions. For example, you can use a +EV setting with Exposure Compensation to get a brighter exposure than the camera is metering the scene. Or, you can use a -EV setting with Exposure Compensation to get a darker exposure compared to the way a camera is metering the scene. Or, you can use shutter or aperture settings to do the same thing if shooting with manual exposure.

Metering is only a tool, and you can change the exposure yourself when you see conditions that you want to handle differently compared to the way the camera is metering a scene. With more experience using a given camera's metering, you'll become more aware of when you may need to use Exposure Compensation to get a darker or brighter exposure compared to the way the camera is metering it for better results.

Also, you've got playback and histogram features on most modern cameras that allow you to quickly review an image and make changes if you want a darker or brighter exposure and take more photos with different settings. Many cameras also have Exposure Bracking available now, so you can automatically take multiple photos, all exposed differently.

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Old Apr 2, 2008, 5:38 AM   #16
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Is there a standard scale which meansures shutter speeds against aperature.

Appart from practise how will one know which aperature to choose at what time ofthe day (time of day reflects amount of light).
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